PSTN vs ISDN vs SIP

PSTN vs ISDN vs SIP

Don’t you just love the abbreviations used when discussing technology, let CNS simplify and decipher this.

Firstly where does this terminology fit in? It is the connection, telephone line, in which your phone or phone system establishes a call to the outside world via a phone services provider, for example British Telecom (BT).

PSTN

Typically if we want a telephone line for voice calls we would have installed a Public Switched Telephone Network (PSTN) line. A single PSTN line has one telephone number allocated to it and allows 1 call at any one time. To enable more simultaneous calls to be made then additional PSTN lines would need to be installed. Simple and straight forward 1 line 1 call. This works well for home/domestic use or businesses who do not need many lines. The installation costs and service rental charges soon escalate to a point where this is not cost effective or sufficiently feature rich to offer the services a digital alternate can offer.

ISDN

Where more lines are required or additional features are necessary telephone system providers turn to ISDN (Integrated Services Digital Network). These type of digital line are provided in two formats, ISDN2e and ISDN30 where ISDN2e carries two trunks or ISDN30 carries up to 30 trunks, a minimum order is 8 channels.

But what is a channel?? A channel is a connection which allows a telephone call to take place therefore ISDN2e provides up to 2 simultaneous calls at once and ISDN30 with 8 channels provide 8 simultaneous calls.

ISDN services can be cost effective where multiple channels are required and additional services such as DDI are also needed. The downside to ISDN is getting the number of lines and therefore trunks correct for the number of calls to be established at peak time. During all other times the investment in telephone services and also hardware to deal with this excess in trunks is costly and unnecessary.

The costs escalate as more lines/channels are required and are installed into a business.

SIP

What is SIP? Session Initiation Protocol

It is the protocol computers use to establish a voice or multimedia connection between two end points across the Internet. Of course in this context we are referring to telephone calls. Utilising existing broadband services the option is available to substitute traditional telephone services Removal of PSTN and ISDN services remove the bottom line costs from a business.

Are the savings really worthwhile?

A Broadband connection per month inclusive of the line is £31.00. A SIP service from CNS starts at £5.50 per month inclusive of 2,000 landline minutes. I’ll let you review your telephone service charges and compare.

CNS can undertake an audit and review of current installations and contracts in place to ascertain if technology changes are suitable for your business.